Document Details
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Document Type |
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Article In Journal |
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Document Title |
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An electron spin resonance, ENDOR, and TRIPLE resonance study of methyl-substituted N,N′-diphenyl-4,4′-bipyridylium dichloride radical cations An electron spin resonance, ENDOR, and TRIPLE resonance study of methyl-substituted N,N′-diphenyl-4,4′-bipyridylium dichloride radical cations |
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Subject |
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Chemistry |
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Document Language |
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English |
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Abstract |
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The e.s.r. and ENDOR spectra of the radical cations of N,N′-diphenyl- 4,4′-bipyridylium dichloride (DPQ), N,N′-bis-(4-methylphenyl)-4, 4′-bipyridylium dichloride (p-mDPQ), N,N′-bis-(3-methylphenyl)-4, 4′-bipyridylium dichloride (m-mDPQ), N,N′-bis-(2-methylphenyl-4, 4′-bipyridylium dichloride (o-mDPQ), and N,N′-bis-(2,4,6- trimethylphenyl)-4,4′-bipyridylium dichloride (T-mDPQ) in methanol were studied over a range of temperatures. Values for the hyperfine coupling constants are given at -40°C. It was found that the radical cation concentrations of DPQ+., p-mDPQ+., m-mDPQ+., and o-mDPQ+. decreased with decreasing temperature, this change being reversible, whilst that of T-mDPQ+. did not. We explain the reversible change with temperature in terms of a monomer-dimer equilibrium, and the absence of such an equilibrium in the case of T-mDPQ+. as due to the lack of planarity of the molecule, because of steric hindrance between the methyl groups and the pyridyl ortho-protons. The thermodynamic constants ΔG°, ΔH°, and ΔS°, obtained for the dimerisation equilibria, are reported. |
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ISSN |
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0300-9580 |
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Journal Name |
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Journal of the Chemical Society, Perkin Transactions 2 |
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Volume |
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1985 |
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Issue Number |
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2 |
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Publishing Year |
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1985 AH
1985 AD |
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Number Of Pages |
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4 |
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Article Type |
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Article |
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Added Date |
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Monday, October 19, 2009 |
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Researchers
| Clack, D.W | Clack, D.W | Researcher | Doctorate | |
| Evans, J.C. | Evans, J.C. | Researcher | Doctorate | |
| عبدالله يوسف عبدالله عبيد | Abdullah Yousif Obaid | Researcher | Doctorate | aobaid@kau.edu.sa |
| Rowlands, C.C. | Rowlands, C.C. | Researcher | Doctorate | |
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